Apparatus for imparting crimp to textile materials of thermoplastic yarn

ABSTRACT

Thermoplastic textile material, either fabrics or yarns, are crimped by passing through a pair of crimping elements, one of which is a heated, engraved, metal roll and the other preferably an unheated roll which has the engraving embossed in it, but instead of leaving this second element after crimping it runs along this element for a considerable distance sufficient to cool the thermoplastic material to its setting point. Preferably where the embossed element is an embossed roll the textile material is carried in the depressions of the roll by a takeup roll or guide positioned below the plane of crimping. After passing over this takeup roll or guide, the material then goes between a pair of conventional outfeed rolls. As the material is heated by the heated roll and softened, it is supported for a longer portion of the periphery of unheated mating roll until it has cooled to a temperature at which the yarn reached its setting temperature, i.e., has lost most of its thermoplasticity and no longer stretches significantly under the very slight tension of outfeed. The result is that the crimp amplitude is maintained more uniform and is deeper, for example 0.03 inch instead of 0.02 inch. This increases bulk and improves dyeability.

United States Patent [191 Yarber I 7 [54] APPARATUS FOR IMPARTING CRIMP TO TEXTILE MATERIALS OF THERMOPLASTIC YARN [75] Inventor: Harold Dean Yarber, Wallace, NC.

[73] Assignee: J. P. Stevens & Co., Inc., New York,

[22] Filed: May 27, 1971 [21] Appl.No.: 147,559

[52] US. Cl ..28/l.8, 28/7215 [51] Int. Cl. ..D02g 1/14 [58] Field of Search ..28/l.2, 1.8, 72.15

[56] References Cited UNITED STATES PATENTS 3,358,344 12/1967 Daniel ..28/1.2 2,988,799 6/1961 Atwell ..28/72. 15 3,462,811 8/1969 Buress et al. 28/72.15 X 3,500,516 3/1970 McClure ..28/1 .2 3,526,936 9/1970 Edmonds "28/12 FOREIGN PATENTS OR APPLICATIONS 1,476,224 2/1967 France ..28/1.8

Primary Examiner-Louis K. Rimrod AttorneyRobert Ames Norton, Michael T. Frimer and Saul Leitner 1 Apr. 10, 1973 5 7 ABSTRACT Thermoplastic textile material, either fabrics or yarns, are crimped by passing through a pair of crimping elements, one of which is a heated, engraved, metal roll and the other preferably an unheated roll which has the engraving embossed in it, but instead of leaving this second element after crimping it runs along this element for a considerable distance sufficient to cool the thermoplastic material to its setting point. Preferably where the embossed element is an embossed roll the textile material is carried in the depressions of the roll by a takeup roll or guide positioned below the plane of crimping. After passing over this takeup roll or guide, the material then goes between a pair of conventional outfeed rolls. As the material is heated by the heated roll and softened, it is supported for a longer portion of the periphery of unheated mating roll until it has cooled to a temperature at which the yarn reached its setting temperature, i.e., has lost most of its thermoplasticity and no longer stretches significantly under the very slight tension of outfeed. The result is that the crimp amplitude is maintained more uniform and is deeper, for example 0.03 inch instead of 0.02 inch. This increases bulk and improves dyeability.

10 Claims, 2 Drawing Figures PATEIx'HD APR 1 0 3 FIG I PRIOR ART FIG. 2

INVENTOR. HAROLD DEAN YARBER AT TOR N EY APPARATUS FOR IMPARTING CRIMP TO TEXTILE MATERIALS OF THERMOPLASTIC YARN BACKGROUND OF THE INVENTION It is common to crimp thermoplastic textile material by passing it between crimping-rolls, one of which is an engraved metal roll which is heated and the other an embossed roll mating with the engraved roll. The material is heated up to the softening point and softened and crimped and then passes out to outfeed mechanisms, which usually include a guide roll and a pair of outfeed rolls. Cooling finally takes place and the crimp is thereby set. As the textile material passes out from between the crimping rolls practically in a straight line and has not had a chance to cool immediately and is still quite plastic, the crimp is straightened out to a considerable extent; and as a result the amplitude of crimping is reduced and hence the bulking of the material, particularly if it is a number of yarns from a beam, is not completely uniform. Neither of these effects is desirable, but theyhave been considered as the necessary price to pay for producing crimped textile material. While normally the outfeed is not under any great tension, it is not possible to avoid slight tension as even the weight of the material, yarn, causes it to sag some, and as it has just left a hot crimping roll it isquite plastic, so that the tension, small though it is, is not negligible.

SUMMARY OF THE INVENTION The present invention uses a heated engraved roll mating with an embossed roll or other element which is not heated and which is, therefore, much cooler than the engraved roll, for example about 100F. cooler. The crimping results just as in the standard procedure but instead of the crimped yarn leaving the rolls or elements while in the heated and highly plastic state, it is supported by the embossed element, such as the periphery of the embossed roll, for a considerable distance and, what is more important, time. The embossed element is preferably an embossed roll mating with the engraved roll but can be any other suitably moving element, such as an endless belt passing between the engraved roll and a pressure roll. This former form of apparatus is preferred and will be described below. A very important feature of the invention is the process performed, and in this aspect the invention is not limited 'tothe particular preferred apparatus in which the embossed element is an embossed roll. The plastic material cools down, for'example nearly to the temperature of the embossed roll, and during this cooling is supported in the depressions in the embossed roll and so does not stretch out significantly. This support is for a sufficient time so that the thermoplastic material cools to a point where it is no longer strongly plastic. This is normally referred to in the art as a setting temperature for the yarn, and the plasticity is so greatly reduced that little or no uncrimp- .ing results under the very slight tension of the outfeed the setting point or temperature is that at which the plasticity of the thermoplastic material has been so greatly reduced that the crimp is not significantly lost as the yarn passes on to the outfeed.

As the thermoplastic yarn is maintained in the depressions of the embossed roll while it is being cooled and is under negligible tension, not even the small tension of the sagging of the yarn in the prior standard procedure, the tension, while theoretically not absolutely zero, is so far below anything that would cause the crimped yarn to be pulled out of the depressions in the embossed roll that it may be considered negligible. The support of the crimped yarn while it is cooling to setting temperature can be effected in any desirable manner. For practical apparatus a very desirable form is a guide roll or guide bar which is positioned below the plane at which crimping takes place so that as the embossed roll turns the yarn lays in its depressions until the yarn setting point is reached. The yarn then is guided up to outfeed rolls or other outfeed mechanisms, which are preferably located above the plane of crimping, as in fact they normally are in the standard procedure. This exposes the set crimped yarn to still further cooling so that when it reaches the outfeed rolls it may be practically at ambient temperature and has lost all of its plasticity, even the negligible residual plasticity at the setting temperature.

The positioning of the outfeed rolls, above the crimping plane, while preferred as it provides still further additional cooling, is not the most important feature of the present invention, which comprises maintaining the crimped and still plastic yarn in the depressions of the embossed roll until it has cooled approximately to the setting point of the particular thermoplastic yarn. The present invention permits maintaining crimp amplitude more uniform and deeper, for example 0.03 inch instead of 0.02 inch or less. This increases yarn bulk and improves dyeability.

It should be noted that the very important process feature of the present invention is the cooling of the yarn while supported by the embossed element. The

particular temperature of the setting point varies with different thermoplastic yarns, and the proportion of the periphery of the preferred embossed roll where the cooling yarn is being supported will vary with embossed roll size, speed, surface temperature and the like. The are of the periphery of the embossed roll over which the cooling yarn is being supported will also vary if external cooling is applied, for example by a blast of cold air on the crimped yarn after it has left the crimping zone, and this can reduce the time needed for cooling. It is also possible to cool the embossed roll artifically by introducing a coolant where the roll is hollow. The invention does not exclude processes and apparatus where additional cooling is used, but it is an advantage of the invention that it is equally applicable to the more standard types of crimping machines where the embossed roll is not subjected to additional cooling. This provides desirable versatility and makes it simple to modify existing crimping apparatus to carry out the process of the present invention.

In the preferred apparatus using an embossed roll and guidepositioned below the plane of crimping the arc of the periphery of the embossed roll over which the textile material is supported can vary widely up to a maximum which for mechanical and structural reasons is an are substantially less than 360.The lower limit of the arc depends to some extent on whether additional cooling is used. The only requirement is that the textile material be supported by the depressions in the embossed element for a sufficient time to reach the setting temperature. A common arrangement of crimping rolls is one in which the embossed roll is of considerably larger diameter, for example about double that of the heated engraved roll, and with such rolls, and with useful speeds, excellent results are obtained by supporting the crimped material for an arc of about 75 to 140 percent of the periphery of the embossed roll. In any event, with unheated embossed rolls it is preferred that the arc of the periphery over which the textile material is supported be at least about ten times the very small are through which actual crimping takes place.

It has been pointed out above that an apparatus with a guide roll or guide bar below the plane of crimping associated with outfeed rolls above this plane is preferred as even more cooling takes place. From the standpoint of practical apparatus this modification has the further important advantage that the improvements of the present invention can be incorporated into existing crimping apparatus by only lowering the guide roll or bar without changing any of the other mechanism. This makes incorporation of the present invention in existing crimping apparatus a simple matter.

The present invention is primarily a process which supports the crimped and quite plastic yarn until it has reached the setting point. The preferred apparatus, which has been briefly described above and which will be described in more detail in conjunction with preferred embodiments below, is included as an apparatus aspect.

The improved apparatus of the present invention is useful for crimping any thermoplastic textile material, such as nylon, acrylics, polypropylene, and the like, and in general the same materials which are useful in the crimping apparatus hitherto used may be used in the improved apparatus of the present invention with the advantages of greater amplitude of crimping, better bulking, and more uniform bulking.

The crimping rolls themselves are not changed by the present invention and may be of standard design. It is common for the embossed roll to have a considerably larger diameter than the heated engraved roll of the stronger material, normally metal, as the latter permits accurate engraving over a much smaller periphery. The

present invention can therefore use the best design of crimping rolls which has been worked out in the past, and so in this respect does not constitute a compromise.

The temperature of the heated engraved roll is not significantly changed by the present invention. In general, as in the past, a range of from around 300F. to 350F. is suitable for most thermoplastic material. The exact temperature will vary, of course, with the materials. With relatively low melting or softening thermoplastics, temperatures nearer the lower end of the range may be used, whereas with higher melting or softening point thermoplastics temperatures nearer the upper range are preferable. The particular temperature of the heated roll is not what distinguishes the present invention from the prior art and it is an advantage that the general operating conditions and equipment of ordinarycrimping rolls can be retained.

The particular nature of the textile material, whether it is woven, knitted or in the form of yarns, is not changed by the present invention, and the improved results of greater crimp amplitude, greater uniformity and better bulking result with the various textile materials used. Here again the present invention does not represent a compromise, and in fact obtains the desirable greater amplitude of crimping and uniformity of bulking without adverse effect on and usually with an improvement in dyeability.

The fact that the crimped textile material is supported on the periphery of the embossed crimping roll under substantially no tension until the thermoplastic has set may be used in various ways. If the rate of throughput of material is maintained constant, the quality and uniformity of the crimp is enhanced. In many cases it is also possible to operate the crimping more rapidly to produce a higher throughput and hence lower costs.

If higher crimping speeds are to be used, it is sometimes desirable to heat the engraved roll to a higher temperature, which would be completely impractical with the standard operation as the even more plastic crimped material would stretch and much of the crimp would be lost. The fact that the present invention can permit more rapid operation and greater throughput is a very real practical advantage as the improved results of the present invention are obtained without offsetting drawbacks. Even the possibility of incorporating the present invention by small modifications of existing machinery is not necessarily thereby compromised as the crimping rolls can be driven at the desired speed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic cross-section of crimping apparatus of the prior art, and

FIG. 2 is a corresponding cross-section of the improved apparatus of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings, in which the same or corresponding elements bear the same reference numeral, the textile material is shown at 6 passing between a pair of crimping rolls 1 and 2, the former being an engraved heated roll, the latter an embossed roll which is not heated. Ordinarily this latter roll is made of a material such as comminuted wool and cotton which is compressed, moistened and run with the engraved roll until the desired embossing is effected. In FIG. 1 the guide roll 5 has its periphery practically at the level that the textile material leaves the crimping rolls and it then passes on up to the two smooth outfeed rolls 3 and 4.

In FIG. 2, which represents the present invention, the roll 5 is lower, so that the material 6 remains in contact with a greater portion of the periphery of the roll 2.

This is indicated by dashed radii. Now the textile material which was heated up by the engraving roll, which, as has been pointed out above, can be at more or less customary temperatures of about 300 to 350F., cools off considerably in the on the roll 2 before it reaches roll 5, and of course it cools still more between roll 5 and outfeed'rolls 3 and 4. The more the textile material is able to cool off after crimping, the more it sets, and the amplitude of the crimp is increased because, in FIG. 1, the effect of the outfeed rolls is to put some unavoidable tension on the material 6, which is augmented somewhat by the weight of the material as it leaves the crimping rolls and before it has reached roll 5 and this tends to straighten it out somewhat, which reduces the amplitude of the crimps and hence the bulking of the material. In FIG. 2, however, the material cannot be stretched during the 90 because the crimps are supported in embossed depressions or grooves of the embossed roll 2, and so as the material cools it cannot stretch. It should be noted that even the slight tension is substantially eliminated as the material cools, and for all practical purposes it can be considered as being supported under conditions of no tension.

After leaving roll 5 in FIG. 2, the material has set but is not completely cooled off, and if any slight stretch then takes place it is insignificant in terms of loss of crimp, and the increased crimp amplitude, better bulking and dyeability of the present invention are retained.

I claim:

1. In a process of crimping thermoplastic textile materials which comprises passing the material between crimping elements, one of them being a heated and engraved roll having an imperforate outer surface and the other unheated and embossed and mating with the engraved roll, the embossed surface said element being imperforate, the improvement which comprises supporting the crimped material in the depressions of the embossed element until the thermoplastic material has reached its setting point, whereby loss of crimp amplitude is substantially eliminated and bulking of the material is higher.

2. A process according to claim 1 in which the embossed element is an unheated embossed roll mating with the heated engraved roll.

3. A process according to claim 2 in which the embossed roll is at least 100F. cooler than the engraved roll.

4. In a crimping apparatus for crimping thermoplastic textile materials, which apparatus includes a heated engraved roll having an imperforate outer sur face meshing with a relatively cool embossed roll having an imperforate outer surface and means for moving the textile material between the rolls, said means in cluding guide means and outfeed means, the improvement which comprises positioning the guide means below the plane of the material entering the crimping rolls so that after crimping the material is supported in the depressions of the embossed periphery of the cool embossed roll, the guide means being positioned sufficiently low so that the textile material is supported by the periphery of the cool embossed roll over an arc sufficient to permit cooling of the thermoplastic material to its setting temperature.

5. An apparatus according to claim 4 in which the outfeed means are a pair of outfeed rolls positioned above the plane of the textile material passing between the crimping rolls.

6. An apparatus according to claim 4 in which the guide means is a guide roll.

7. An apparatus according to claim 6 in which the guide roll is positioned sufficiently low so that the textile material is supported by an arc of the periphery of the cool embossed roll at least about ten times the arc durin which crimping takes place.

8. in apparatus according to claim 6 in which the outfeed means are a pair of outfeed rolls positioned above the plane of the textile material passing between the crimping rolls.

9. An apparatus according to claim 4 in which the guide means is positioned sufficiently low so that the textile material is supported by the periphery of the cool embossed roll over an arc at least about ten times the arc during which crimping takes place.

10. An apparatus according to claim 9 in which the outfeed means are a pair of outfeed rolls positioned above the plane of the textile material passing between the crimping rolls. 

1. In a process of crimping thermoplastic textile materials which comprises passing the material between crimping elements, one of them being a heated and engraved roll having an imperforate outer surface and the other unheated and embossed and mating with the engraved roll, the embossed surface said element being imperforate, the improvement which comprises supporting the crimped material in the depressions of the embossed element until the thermoplastic material has reached its setting point, whereby loss of crimp amplitude is substantially eliminated and bulking of the material is higher.
 2. A process according to claim 1 in which the embossed element is an unheated embossed roll mating with the heated engraved roll.
 3. A process according to claim 2 in which the embossed roll is at least 100*F. cooler than the engraved roll.
 4. In a crimping apparatus for crimping thermoplastic textile materials, which apparatus includes a heated engraved roll having an imperforate outer surface meshing with a relatively cool embossed roll having an imperforate outer surface and means for moving the textile material between the rolls, said means including guide means and outfeed means, the improvement which comprises positioning the guide means below the plane of the material entering the crimping rolls so that after crimping the material is supported in the depressions of the embossed periphery of the cool embossed roll, the guide means being positioned sufficiently low so that the textile material is supported by the periphery of the cool embossed roll over an arc sufficient to permit cooling of the thermoplastic material to its setting temperature.
 5. An apparatus according to claim 4 in which the outfeed means are a pair of outfeed rolls positioned above the plane of the textile material passing between the crimping rolls.
 6. An apparatus according to claim 4 in which the guide means is a guide roll.
 7. An apparatus according to claim 6 in which the guide roll is positioned sufficiently low so that the textile material is supported by an arc of the periphery of the cool embossed roll at least about ten times the arc during which crimping takes place.
 8. An apparatus according to claim 6 in which the outfeed means are a pair of outfeed rolls positioned above the plane of the textile material passing between the crimping rolls.
 9. An apparatus according to claim 4 in which the guide means is positioned sufficiently low so that the textile material is supported by the periphery of the cool embossed roll over an arc at least about ten times the arc during which crimping takes place.
 10. An apparatus according to claim 9 in which the outfeed means are a pair of outfeed rolls positioned above the plane of the textile material passing between the crimping rolls. 